1. Field of the Invention
This invention relates to integrated circuits (including hybrid circuits and multichip modules) and, in particular, to a plastic packaged integrated circuit including semiconductor die or dice, package leads, bond wires, an optional heat sink having a surface exposed outside the plastic, and a thermal induction plate, which radiates less electromagnetic energy, has reduced electrical noise and crosstalk, and dissipates heat well.
2. Related Art
Increased semiconductor production volumes have led to the development of more cost effective integrated circuit packaging, e.g., plastic packages. However, the conventional plastic package has poor thermal conductivity, making it disadvantageous for use with modern integrated circuits which are subject to greater heat buildup than their predecessors due to increased speed of operation and/or to increased density of electrical circuitry on the integrated circuit chip. In order to provide improved thermal performance (i.e., improved dissipation of heat), some plastic packaged integrated circuits now include a metallic heat sink to aid in the removal of heat from the semiconductor die to the exterior of the package.
In addition to considerations of cost and heat dissipation, it is desirable to package an integrated circuit so as to minimize the amount of electrical noise generated. Switching noise (for instance, an inductive voltage spike that occurs on a current path as the result of rapid current switching) and crosstalk (the appearance of a spurious electrical current in a current path as a result of mutual capacitance and inductance between such current path and other nearby current paths) are two significant sources of noise in integrated circuits. In packaged integrated circuits including leads to transmit electrical signals between the integrated circuit chip and electrical components outside the package, mutual inductance and self-inductance of these package leads are particularly troublesome sources of electrical noise.
Another problem associated with packaged integrated circuits is electromagnetic interference (EMI). Electromagnetic radiation that emanates from the electrically conductive material within a conventional plastic package can interfere with nearby electronic components. It is desirable to minimize or eliminate this electromagnetic interference.
In today's packaged integrated circuits, it is desirable to include one or more generally conductive layers including electrically conductive regions and/or paths within the package for use as power, ground or routing planes. Power and ground planes enable provision of more uniform power and ground supplies to the integrated circuit chip. Routing planes allow increased flexibility in the formation of electrical connections within the packaged integrated circuit. The provision of such generally conductive layers is also desirable because, properly configured, the generally conductive layers can help reduce electrical noise. For instance, a generally conductive layer, when formed into a power or ground plane, can be used to increase decoupling capacitance, reduce the length of signal paths, and reduce capacitive and inductive coupling between adjacent signal paths in order to minimize switching noise and crosstalk.
Despite the aforementioned efforts at improving heat dissipative capacity and electrical performance, there is a continuing need for packaged integrated circuits having increased heat dissipative capacity and improved electrical characteristics such as reduced electrical noise and EMI.